The present invention relates to a new and improved construction of a clinically usable pump apparatus for a dilatation device having a dilatation catheter, preferably for opening stenoses and occlusions or for closing vessels, ducts and openings, while using a pumpable medium.
Based upon the work of Doctors Charles T. Dotter and Melvin P. Judkins (Transluminal Treatment of Arteriosclerotic Obstruction. Circulation 30, pages 654-670, 1964) there have been developed spherical-shaped, balloon-like dilatation catheters which can be positioned at the site of the stenosis and expanded by pressurized water supplied internally of the catheter. No pressure control is possible with this equipment. In order to pressure relieve the dilatation catheter a vent to the atmosphere is opened.
What is disadvantageous with this equipment is that the reduction in pressure, especially at the lower pressure region when approaching atmospheric pressure and due to the narrow flow paths, only can be accomplished extremely slowly and unsatisfactorily. As a result the dilatation catheter remains in a dilated state for a relatively long period of time, although it is exactly in medical applications that rational operation is extremely valuable. Venting into the atmosphere does not preclude air from reentering the dilatation catheter and when encountering unfavorable conditions such air possibly entering the bloodstream. Without any pressure control the momentarily attained dilatation cannot be predicted ahead of time and the danger exists of localized overloading at the treated site.